Starting from pure metals and sulphur in evacuated silica tubes single crystals of Cu Ni Sn S have been obtained by heating at 8 4 12 32 ] ° 7508C. It crystallizes in the Fd 3m space group with Z51 and a510.3022 (6) A. The atomic parameters and anisotropic thermal parameters were refined to give a final R value of 0.0157. The mode of filling of tetrahedral and octahedral cavities of the anionic close packing has been analyzed taking their sizes into account. The difference in space groups for the analogous Fe and Cd thiospinels (I 4 /a) 1 ] 21 21 compared to that of the title compound (Fd 3m) appears to be due to the larger size of the Fe (HS) and Cd ions leading to distorted 2 octahedra. Cu Ni Sn S shows semiconducting behavior with resistivity of 10 V-cm at room temperature with a small band gap 8 4 12 32 (|0.05 eV).